In many applications including directed energy weapons systems, it is desirable to both transmit outgoing pulses of high energy laser light and to receive reflected return energy from a target during the interpulse intervals along the same but reciprocal optical path. Such systems are called upon to separate the outgoing and received optical energies along a common optical aperture, to detect the relative mis-alignment therebetween, and to correct the relative misalignment between the outgoing and received optical energies to maintain subsequent pulses both on-target and in-focus.
One impediment to the utility of such systems is thermal loading. As the outgoing laser energy is produced, it is partly absorbed as heat by the cavity mirrors of the optically active cavity. The mirrors thermally expand, changing their figure, which therewith throws the outgoing laser pulses out of focus. In addition, both the phenomena of edge diffraction off of the cavity mirrors and that of intracavity turbulence tend to break up the high energy laser beam formation process. Such systems are thus further called upon to provide an outgoing beam of high energy laser light in a manner that is substantially free of the undesirable effects of cavity mirror thermal loading, intracavity turbulence, and cavity diffraction-feedback.